Piano key switch



Jan- 28, 1958 D.' G. KIMBALL ETAL 2,821,582

PIANO KEY SWITCH' Filed Sept. 5, 1957 United States Patent C PIANO KEY SWITCH Donald G. Kimball, Stratford, and Albert J. Gartland, Jr.,

Shelton, Conn., assignors to General Electric Company, a corporation of New York Application September 3, 1957, Serial No. 681,552

7 Claims. (Cl. 200-18) The present invention relates to an electric switch and particularly to a multiple push button switch having a plurality of piano keys for operating the push buttons.

This invention is an improvement over the push button switch of the basic Andrews Patent No. 2,431,904 which is assigned to the same assignee as is the present invention. Multiple push button switches have been used for many years on electric ranges. In recent years the field of use has been expanded to include electric window fans, electric broilers, and automatic washing machines.

One purpose behind this invention is to change the styling of a push button switch by adopting piano keys in place of the usual push buttons. The piano keys are made much wider than the individual push buttons so that means must be provided to link the wide piano keys to the narrow push buttons of the push button switch.

The principal object of this invention is to provide a multiple push button switch with a plurality of piano key actuators.

A further object of this invention is to provide a multiple push button switch with piano key actuators that will be held in perfect alignment in both the outer and depressed positions.

A further object of this invention is to provide a piano key switch with positive stop means for the keys in both the outer and depressed positions.

A still further object of this invention is to provide a multiple push button switch with wide piano key actuators, and means for connecting the end keys to the push rods of the push button switch.

The principal requirement of the present switch is that it have piano key actuators arranged in close side-by-side relation for operating a multiple electric switch. Our invention is to mount a standard multiple push button switch on one side of an elongated bracket and provide openings in the bracket for receiving a plurality of push rods of the switch therethrough. On the opposite side of the bracket a plurality of wide piano keys are pivotally mounted on a common axis so that the depression of one of the keys in the manner of a second class lever will operate one of the push rods of the switch.

. The keys are quite wide as compared with the narrow spacing between the push rods of the switch so that only the innermost keys bear directly on their particular push rods. The two end keys are arranged off to the sides of the push rods so that special means must be provided toconnect each end key with one of the push rods. lThis isaccomplished by a pivoted lever mounted on the cornmon pivotal axis of the keys and under each end key. Each lever is formed from a thin plate with one edge having an extension turned at right angles to engage the underside of the end key. Adjacent the opposite end of the lever an oversized slot or window is formed in the plate material for receiving the endmost push rod therethrough for operation by the key next to the end key. The far end of the lever remote from the end key is arranged f t engagea push rod of reduced length which happens "ice to be the one next tothe endmost push rod mentioned previously. Detent springs are provided to bear against the keys and secure perfect alignment in both the outer' and depressed positions as well as prevent the keys from` rattling due to vibrations. Also, a spring means is provided between the end key and the underlying lever to hold the lever in engagement with the key to avoid lost motion so that the feel of each key will be relatively the same.

Our invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Fig. 1 is a front elevational view of a piano key switch embodying our invention as it would be mounted in the face of the back-splash of an automatic washing machine.

Fig. 2 is an isometric view of the piano key switch of Fig. 1 with the three right-hand keys removed to reveal the construction of the mounting bracket and the pivoted lever.

Fig. 3 is a right end elevational View of the switch of Fig. 1 with the end key in its outer position.

Fig. 4 is an end view similar to Fig. 3 with the end key in its depressed position.

Referring in detail to the drawing and in particular to Figs. 2 and 3, there is shown an elongated mounting bracket 10 supporting on its front side a plurality of wide piano keys 11 and on its back side a standard multiple push button switch 12 as shown in dotted lines in Fig. 1.` Such a switch 12 has a plurality of parallel push rod actuators 13 arranged in a row and extending outwardly through one wall of the switch housing. It should be noted that there are five keys 11, while there appears to be six push rods 13 shown in Fig. l. For inventive purposes a standard six-position push button switch 12 is used in order to obtain the desired spacing between the push rods. Since there are ve keys 11, only tive push rods are necessary; therefore, the push rod that is the third from the left side has been eliminated as shown at 14 in Fig. 2. The mounting bracket 10 is generally of L-shape in cross section and it has a long leg 15 with a series of six rectangular openings 16 for receiving embossments 17 of the housing of the switch 12 that surround the push rods 13. Rivets, or other suitable fasteners (not shown), are used to attach the push button switch 12 to the back side of the leg 15 of the bracket. The five keys 11 are all pivotally supported on a single rod 20. This-rod is in turn supported by a series of parallel tabs 21 that are staked in slots in the leg 15 of the bracket. Each tab 21 contains an opening 22 in perfect alignment with similar openings in the other tabs so that the pivot rod 20 may be threaded through the tabsr without interference.

All of the piano keys 11 are identical and they comprise a hinged end 25, a finger piece 26, and a lower distal end 27. The hinged end 25 has a bearing28 at each side` separated by an open space 29. 'The inward movement of the keys 11 to the depressed position is limited by the push rods 13 of the push button switch. This relation-v ship is not maintained however, when the depressed push rods 13 move outwardly to return the keys to their outer position. This is due to the lack of a connection between the keys and the push rods 13. Hence, the short. leg 30 of the mounting bracket 10 has a longitudinal edge 31 `with a plurality of small tabs 32 which are folded upwardly to serve as stop means for the keys in the outermost position of the keys. As shown vin Fig. 3, the lowerend 27 of the key bears against the tab 32 to insure of the keys will be imperfect alignment.

Since this type of piano key switch' has found its great-tasty assigne use in automatic washing machines, mechanical vibration is a factor which must be considered. It has been found expedient to include an indexing or detent spring 33 to exert a small spring force on the lower end of the key 11 in both its outer and depressed positions. The spring 33 has a cantilever action with one end fixed to the leg 15 of the bracket. The free end of the spring '33 has a convex surface 34 on its top side. Looking atFig. 3, the convex end 34 of the detent spring is engaged behind the lower end 27 of the key 11 to hold the 'key against the stop means 32 and insure the perfect alignment of the keys in the outer position. The lower end 27 of each key 11 is further provided with an indentationBS so that when the key is depressed, the convex end '34 of the detent spring will snap into the indentation and temporarily hold the key in place as best seen in Fig. 4.

Turning now to a consideration of Fig. l, it will be understood that the two endkeys do not overlie the push button switch 12. However, the three innermost keys are in a proper position over the switch l2 for engaging the push rods 13. Reading from left to right in Fig. l, the second key engages the first push rod, the third or middle key engages the fourth push rod, and the fourth key engages the sixth and last push rod. As explained .so far, the two end keys, the first and the fifth, have not been connected to the push rods of the switch 12. The second and fifth push rods 13 are available so that the first `key 1'1 must be joined with the second push rod while the fifth key must be joined with the fth push rod.

A lever 40 of thin plate material, as seen in Fig. 2, is arranged under each end key for transmitting the inward force of the end key to its related push rod. In Fig. 2, the three right-hand keys have been removed so that a study maybe made of the lever 40 and its relationship with the right-hand end key. The plate 40 is supported on the rod by a pair of hinge ears 41; one ear being straddled by the bearings 28 of the fifth or end key, while the other ear is straddled by the bearings 28 of thefourth key. As a result, the lever pivots on the same pivotal axis as the keys 11. The edge of the lever 4t) opposite the hinged ears 41 contains an extension 42 bent at a right angle to `engage the underside of the end key l11. This extension 42 is toward one end of the lever, while at the other endthelever bears against the top of the yfifth push rod 13, although it isnot visible in Fig. 2. This -fifth pushrodis of reduced `length ascompared with therst, fourth, and ,sixth ,push rods. The push rods that bear directly .on Vthe innermost keys 11 arelonger than the push rods that bear `against the levers because ythe levers are disposed under the keys.

lSince the, lever 40 overlies `the sixthpush rod, an oversized slot or window 43 is made in the lever thereby enabling the sixth push rod to extend therethrough and be independent ofthe lever 40. The downward force ofy the end key 11is exertedagainst the extension 42 at one-end of the lever 40 in order to transmit a downward force at the other end of the lever to the push rod. Because of the turning movement `acting on the lever 40, a stop meansis necessary .to limit the amount that the end keys maybe depressed. This is provided by a lanced `projection 45 in the leg 15 of the bracket that is engaged by the lever, `as shown rin Figs. 2 and 4.

Another point to control vibrations would be between the end buttons 11 and underlying levers 40. This problem is solved by the use of a straight wire spring 46, shown in Fig. 2, confined yat its ends behind the bearings 28` of the end key 11, while vitscenter is strung over the free end of one of the ears 41rof the lever 4t). Thisspifing 461 exerts a small clockwise force against the lever 40 to bias the lever into a position where its extension 42 engages the underside .of the key, 11.

Having described` above our invention of anovel piano key switch using in combination a standard push button switch and ,means for adopting piano key actuators, it

. 4 should be readily apparent to those skilled in this ar that we have improved `the styling -as lwell as the easeof operating a push button switch. We have also provided such a key operated switch with several kinds of detent spring means that eliminate mechanical noises from rattles when such a switch is used as part of high speed equipment such as automatic washing machines.

Modifications of this invention will occur to those skilled in this art and it is to be understood, therefore, that this invention isnot limited to the particularembodiments disclosed but that itis `intended :to cover all modifications within the true spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A key-operated electric switch comprising in combination a multiple push button switch supported on an elongated mounting bracket, the push button switch being operated by .a plurality of parallel pushl rods arranged in one wall of the switch in close side-by-side relation, the push rods extending through openings in the bracket, a plurality of .keys pivotally mounted about a common axis on the side of the bracket opposite the push button switch, the keys being relatively wide and covering a much greater expanse `than lthe push rods, some Vof 'the keys bearing directly on a separate push rod, at least one key at one end being `positioned off to the side of the push rods, `a pivoted lever supported on the common pivotal axis of the lkeys and extending under said one end key, Hthe saidA lever having an oversized slot for receiving the push rod that is operated by the key that is adjacent said end key, .the end of the lever remote from the saidV end -key bearing against a Vpush rod of reducedlength, so that each key will control the operation of 'a separate push rod of "the, push button switch.

2. A key-operated electric .switch as recited in claim l with -the provision of detent means on the bracket 'that bears against each key and exerts a small force to prevent the keys from rattling 4in both their outer and depressed positions. i

3. A key-operated electric switch as recited in claim 2 wherein a spring member is biased against the saidjlever to hold the lever in engagement with the said yend key.

4. A key-operated electric switch comprising in com-` bination a multiple push button switch supported on an elongated mounting bracket, la plurality of parallel push rods arranged in one wall of the push button `switch in; close side-by-side relation, and openings inthe bracket through which the push rods extend, a plurality of 'keys in close side-by-side relation pivotally mounted about a common axis on the side 4of the bracket opposite the push button switch, the keys being relatively wide and covering a much greater expanse than the push rods, each of the innermost keys bearing directly on a separate push rod, each of -the two end keys rbeing positioned off to the sides of the push rods, each end key having a pivoted lever supported `on the common pivotal axis of the keys and extending under the end key, each leverhaving an oversized slot for receiving the push rod thatI is operated bythe key next Ato the end key, the end of the lever-remote fromy the said end key `bearing against a push rod ofreduced length, and stop means arranged on the bracket to limit 'the inward pivotal movement of the lever, and a second stop means provided on the bracket for each key to limit the pivotal movement of the key awayffrom its push rod, .and spring means pro` vided on the bracket and bearing against each key to exert a small springforce against the key and prevent the keys -from rattling -in both their outer and depressed positions.

5. A keyeoperated electric switch as recited in claim 4 wherein the said spring means `is a cantilever spring with a convex -end portiony that engages behind each key when the key `is in. itsouter position to hold the key against its stop means, each key having an indentation on its end removed from its pivotal end whereby the concavq s portion of the detent spring will engage in the indentation when the key is in its depressed position.

6. A key-operated electric switch as recited in claim 5 wherein the common pivotal axis of the keys and levers for the end keys is established by a single pivot pin that extends through all of the pivoted members and supports them on the mounting bracket.

7. A key-operated electric switch comprising in combination a multiple push button switch supported on an elongated mounting bracket, the push button switch including a plurality of parallel push rods arranged in one wall of the switch in close side-by-side relation, and openings formed in the bracket for receiving the push rods therethrough, the mounting bracket being generally of L-shape with a long and a short arm, the long arm of the L bracket including the openings for receiving the push rods of the push button switch, a plurality of upright members arranged on the long arm of the bracket in parallel spaced relation, and an elongated pivot pin extending through the upright members and supporting a plurality of pivoted keys for operating the push rods of the push button switch, the keys being relatively wide and covering a much greater expanse than the push rods, each of the innermost keys bearing directly on a separate push rod, the two end keys being disposed to the side of the push rod, and a pivoted lever for each end key having the shape of a thin plate and pivotally mounted on the common pivotal axis of the keys, one end of the lever having an extension that bears against the underside of the end key while the opposite end of the lever is in engagement with a push rod of reduced length, the lever including an oversized slot for receiving the push rod that is operated by the key next to the end key, and detent springs for each key to exert a small force against the keys in both the outer and depressed positions to prevent them from rattling and to hold them in alignment, and spring means, combined with each lever and arranged between the end key and the lever to hold the lever always in engagement with the end key and avoid lost motion.

References Cited in the tile of this patent UNITED STATES PATENTS 

